Heat exchanger and method of making same



April 2, 1963 Il HIT-'TIITHED ll llll llll J ll HV1-'Till llll Il l Il llll ll I j' I I Il HH III H ll 1 z l1 R. C. ZEIDLER HEAT EXCHANGER AND METHOD OF' MAKING SAME Filed July 19, 1957 ,funverz/v: fige rz/UZJCZeL'dZer BSBhZ Patented Apr. 2, 11953 3,083,562. SEAT EXtXiNGF-JR ANB hr-ETHD F Stall/EE Reinhold C. Zeidler, Betr-oit, Mich., assigner to Borg:

Warner Corporation, lll., a corporation or illinois Filed July 19, i957, Seru. No. 672,937 2 Claims. (El. l--l rl`his invention relates -to heat exchangers and more particularly to a turbulizer for edecting turbulence of liquids such as oil and the like during the course of passage through a heat exchanger, and thus more elective heat dissipation. The present heat exchanger is of the tubular type and is particularly suitable for cooling the oil of torque converters in automatic transmissions for vehicles and the like where compactness is of importance.

Heretofore, oil coolers of this type have been provided with turbulizers comprised of a pair of hollow semi-cylindrical complementary grids for reception in a correspondingly formed passage of a tubular heat exchanger to retard the llow of oil, increase turbulence and enhance the eciency of heat trans'ter. These turbulizers have been formed from tlat ribbon stock and have been characterized by longitudinally aligned groups of parallel slits delining staggered U-shaped portions offset from the plane of the ilat stock. The material between each pair of adiacent slits in a group was positioned at opposite sides of the original plane of the sheet to form the U-shaped portions. The U-shaped portions were longitudinally spaced from each other and the adjacent staggered series of U-shaped portions so that a sinusoidal path was formed for two separate streams of oil through the annular passage. By this arrangement, stratiiication of the oil occurred because of the two separate paths or" flow and heat transfer was diminished because of the fact that only part or` the U-shaped portions were in conductive relation to the heat exchange surface.

Accordingly, a principal object of the invention is to provide a tubular heat exchanger having a turbulizer formed to the conguration or an annular chamber without decreasing the eciency and effectiveness of the turbulizing unit.

A vfurther object of the invention is to provide a heat exchanger of the stated type having a turbulizer which is capable of effecting a high degree of turbulence in the heat exchanger, and lwhich is provided with relatively large conductive surfaces to facilitate the dissipation of heat.

Another object of the invention is to provide a turbulizer of the mentioned type which is characterized by radially extending longitudinally spaced groups of corrugations oiset from the plane of the stock in the one direction, in which alternate series of corrugations of a group are partially oiset longitudinally so that they overlap adjacent series of corrugations and thus assure turbulence in the oil during the course of iloW through the annular heat exchange chamber, and in which the adjacent series of corrugations are joined on a common plane coincident with one side of the turbulizer so that forming of the unit to the required semi-annular shape is facilitated.

A further object of the invention is to devise a method for forming the turbulizer of lthe present invention in which a continuous strip of flat metal is provided with longitudinally spaced groups of longitudinally extending parallel slits, in which the strips deiined by the slits are formed into laterally extending corrugations, in which the corrugations are reformed to offset longitudinally alternate series of strips, in which the ilat grid thus formed lis bent to assume a semi-annular shape in cross-section and in which the grid is severed to the required length.

A nal object of the invention is to provide a turbulizer of the stated type which is characterized by ease of manulfacture, facility of use, convenience in form, and improved functional characteristics.

This invention consists of the novel constructions, arrangements, and devices to be hereinafter described and claimed for carrying out the above stated objects and such other objects as will be apparent from the following description of preferred forms of the invention, illustrated with reference to the accompanying drawings, wherein:

FIGURE l is a plan view of a section of tlat ribbon stock used to form the turbulizer of the present invention;

FIGURE 2 is a fragmentary plan View of the at stock of FIGURE l after the slitting step;

FIGURE 3 is an enlarged elevational View of the stock in the stage shown in FIGURE 2;

FIGURE 4 is a plan view similar to FIGURE 2 but showing the stock in the conguration it assumes after the transverse corrugation step;

FIGURE 5 is an enlarged elevational View of the preform in the stage illustrated irl FIGURE 4;

FIGURE 6 is a plan View similar to FIGURES 2 and 4 showing the stock aiter it has been reformed to stagger the corrugations in alternate series of strips joined t0- gether only at the base which is substantially coincident with the original plane of the stock;

FIGURE 7 is an enlarged elevational view of the preform shown in FIGURE 6;

FIGURE 8 is a greatly enlarged View in perspective of the turbulizer preform in the stage illustrated in FIG- URES 6 and 7;

FIGURE 9 is an elevational view of a turbulizer section in its iinal configuration; and

FIGURE l() is a sectional View of a heat exchanger embodying a pair of complementary turbulizer sections of the type shown in FIGURE 9.

Referring -to the drawings and more particularly to FIGURES 9 and 10, the heat exchanger of the present invention is indicated generally by reference numeral 6 and may comprise an outer housing 7, an inner casing 8 within the housing 7 and defining therebetween -a substantially annular passage 9 for flow of a suitable coolant, and a tubular conduit l1 in spaced relation to ythe casing S and defining therebetween -a substantially annular passage i3 for the oil to be cooled. The housing 7 may be omitted and the casing 3 may be arranged in the bottom tank of a radiator or in a tubular conduit such as a hose connection between the vehicle engine and the radiator. In cases where the housing 7 is utilized the coolant may ilow in parallel through the conduit l1 as well as through the passage 9. The passage i3 may be closed 4at each end by any suitable means and the oil may be introduced through an inlet 13a and discharged through a suitable outlet (not shown). It will be understood that the present heat exchanger is characterized by compactness and that the axial extent of the passage -is limited. Thus, it is important to retard the rate of How of the oil and bring the oil into intimate contact with the surfaces of the wall of the conduit 1l and the casing 8 -so that maximum heat transfer may be eiected. This result is accomplished by a turbulizer di) which, in the present instance, comprises two complementary sections lila and ltlb extending substantially the full length of the chamber i3. rl`he turbulizer lti is in the form of a grid providing a tortuous passage for the oil to be cooled and is formed from flat metal stock which, as will be hereafter apparent, is shaped to provide a series of obstacles to the oil flow. The shaping of the obstacles, according to lthe present invention, is accomplished in such a manner as to facilitate the forming of the turbulizer to the shape shown in FIGURES 9 and l0.

Referring now to FIGURE 8, the turbulizer is shown fragmentarily in that figure on a greatly enlarged scale, in the shape it assumes just prior to [forming to the configuration of the chamber 13. The turbulizer 10' has a base and a plurality of longitudinally spaced groups 17 of substantially U-shaped corrugations extending in Vone direction from the plane ofthe base 15.V These groups 17 extend transversely of the blank or flat stock during formation'and radially outwardly from the base 15 when the ,turbulizer section is shaped as in FIGURESQ and l0. Each of the groups 17 includes a series of l.spaced corrugations 14 and an alternate series of longitudinally olfset corrugations 16. The several corrugations 14 and x16 are `joined only to the base 15 and thus when the preform shown in FIGURE 8 is shaped as in FIGURES 9 and l0, the portions of the base 15 connecting the several longitudinally spaced corrugations 14 and the portions of the base 15 connecting the several longitudinally spaced corrugations 16 form joined chords of such limited dimension that -a high degree of heat conduction is afforded through the turbulizer and through the wall of the conduit lll. To effect ecient heat conduction through the casing -8 each of the corrugations is preferably shaped so that a substantial area is in contact with the casing. To this end, each of the corrugationsfhas a substantially llat top panel 14a while each of the corrugations y16 has a Asubstantially hat Vtop panel 16a.

The offset arrangement and shape of the corrugations 14 and 16 provides for effective turbulization and the prevention of stratification of the oil along the heat conductive surfaces. kEach of the corrugations 14 has a sloping upstream panel 1llb and a sloping downstream panel 14C while each of the corrugations 16 has a sloping up- -stream panel 16h and a sloping downstream panel 16e. Assuming flow of oil in the direction of the arrow in FIG- URE 8, the oil impinges against the panel' 14h of the several corrugations 14 and thence passes therebetween into vengagement with the leading or upstream panel 16b of the several corrugations 16. The oil then flows through openings 19 between the upstream panels of theV several series of corrugations, thence into contact with the inner surface of each downstream panel 16e, and thence out through openings 21 between the downstream panels of the corrugations of adjacent series. -It will be apparent that the above cycle is repeated when the next group of corrugations is reached and that the oil traverses a series of substantially right angle turns during the course of its passage through the several groups of corrugations. These sudden changes of course or the oil provides an efficient scouring -action which precludes the formation of film of cold oil on the surfaces of the casing 8 and the wall of the conduit 11.

According to the method of the present invention, the turbulizer l() may be formed from a continuous ribbon olf at stock, such as shown in FIGURE l, and is initially subjected to a slitting step, as shown in FIGURES 2 and 3. This slitting step may be effected by passing the ribbon stock through -a Irotating slitter (not shown) having suitably positioned cutting elements to alord longitudinally spaced groups of transversely extending parallel elongated slits 12. The strip material between adjacent pairs of slits 12, as will be apparent is subsequently utilized to form the corrugations 14 and 16. As the slits 12 are formed, the longitudinally spaced groups or sections are separated by a series of depressed zones which facilitate the forming of the turbulizer during the subsequent steps into the V tions :14 and 16 are offset from the plane of the stock n one direction. During this step the stock is subjected to suitable forming apparatus, Such as supplementary forming rolls (not shown) having circumferentially spaced lands for corrugating the stock in a manner that the co-rrugations 14 and 16 are in transverse alignment.

The preform shown in FIGURE 5 is then subjected to a reforming step in which the series of corrugations 16 is offset longitudinally from the series of corrugations 14.

The flat preform shown in FIGURES 6, 7 and 8 may be shaped to the final form shown in FIGURES 9 and l0 on a mandrel of suitable diameter about an axis parallel to the corrugations. In this connection, it will be noted that the several corrugations of the adjacent series, 14 and 16 are joined only at one plane, i.e. the base 15. By this arrangement, the formation of Ithe preform of FIGURES 6-8 to the final form shown is facilitated and the several segments of the base 15 are maintained in good heat exchange relation with the surface of the conduit 11. 'The flat top panels of the corrugations 14 and 16 are at the same time in good heat exchange relation with the inner surface of .the casing 8.

Thev stock may be severed to the desired length either before or after the forming of the blank into an arcuate shaped section.

The present heat exchanger provides a turbulizer which is characterized by an eicient and effective .turbulizing action as well as providing a planar base section for efcient dissipation of heat through the coolant flowing through the conduit 11 'and flat top panels for effective Vheat conduction through the casing 8 to the coolant passing through the passage 9. Furthermore, the longitudinal skilled in the art that changes may be made without de parting from the principles of the invention.

Iclaim:

1. A method forY forming a turbulizer for a heat ex,-v

changer comprising the steps of slitting a continuous ribbon of dlat stock to form a plurality of longitudinally spaced transversely extending groups'of contiguous strips, corrugating the said groups of strips to fashion a preform having a plurality of longitudinally spaced groups of corrugations, reforming said corrugations to form alternate series of corrugations offset longitudinally from each other, shaping said stock about an axis parallel to said strips so that it assumes an arcuate configuration and severing said stock to the required length. Y

' 2. A method for forming a turbulizer comprising the steps of slitting a continuous ribbon of flat stock to form a plurality of longitudinally spaced transversely extend- Ving groups of contiguous strips, corrugating the said groups of strips to fashion a preform having a plurality 'of longitudinally spaced groups of corrugations joined 'only at a base, reforming said corrugations to form alternate series of corrugations offset longitudinally from 'each other, shaping said stock about an axis parallel to said strips so that it assumes an arcuate configuration and severing said stock to the required length.

References Cited in the file of this patent UNITED STATES PATENTS 2,360,123 Gerstung er a1 ocr. Y10, 1944 2,627,283 Przyborowski Feb. 3, 1953 2,752,128 DedO .lune 26, 1956 

1. A METHOD FOR FORMING A TURBULIZER FOR A HEAT EXCHANGER COMPRISING THE STEPS OF SLITTING A CONTINUOUS RIBBON OF FLAT STOCK TO FORM A PLURALITY OF LONGITUDINALLY SPACED TRANSVERSELY EXTENDING GROUPS OF CONTIGUOUS STRIPS, CORRUGATING THE SAID GROUPS OF STRIPS TO FASHION A PERFORM HAVING A PLURALITY OF LONGITUDINALLY SPACED GROUPS OF CORRUGATIONS, REFORMING SAID CORRUGATIONS TO FORM ALTERNATE SERIES OF CORRUGATIONS OFFSET LONGITUDINALLY FROM EACH OTHER, SHAPING SAID STOCK ABOUT AN AXIS PARALLEL TO SAID STRIPS SO THAT IT ASSUMES AN ARCUATE CONFIGURATION AND SEVERING SAID STOCK TO THE REQUIRED LENGTH. 